Surface Arcover in DC Capacitors

Data useful in the design of dc capacitors have been taken on the voltage for arcover V
A
across a distance d on the surface of an insulating polymer film. It is found that VA (kV) = 3d (mm)
^0.55
for arcover in air at p = 83 kPa, T = 20°C and 30 percent RH. The equation applies to buried foil capacitors and to an electrode configuration that simulates a single turn of an extended foil capacitor. For extended foil capacitors it is found that V
A
increases as 1.0d
^0.90
.